Shower arm



FIG. 1 is a rear perspective view of our new design for a shower arm;

FIG. 2 is a left side view thereof, the right side being the same as the left side;

FIG. 3 is a bottom view thereof;

FIG. 4 is a top view thereof;

FIG. 5 is a front view thereof; and,

FIG. 6 is a bottom view thereof. 

The ornamental design for a shower arm, as shown and described. 